1. Field of the Invention
This invention relates generally to fish farms, and, more particularly, to improvements in fish farms of the type in which the fish are raised in an open tank or raceway through which water is circulated to permit fecal matter and other waste to be removed therefrom and thus reduce bacteria in the water.
2. Description of the Prior Art
U.S. Pat. No. 4,244,486 shows an open tank which is especially well adapted for use as "raceway" of this type. In order to reduce its bacterial content, air may be injected into the water through air stones or jets suspended in the tank. Preferably, the jets are so arranged around the perimeter of the tank as to induce circulation in a generally horizontal path which is intended to direct the waste to a place of disposal. However, due to the length of tank, and hence the long path of circulation, the waste tends to settle out and must be removed through standpipes.
It is often necessary in fish cultures of this type to separate certain types of fish from one another or to separate the smaller fish from the larger fish of the same type. It is also known that some types of fish are heartier than others and thus able to grow in water having higher waste particles level than others.
Water is of course a scarce as well as expensive commodity. Hence, as the water leaves the tank, it is preferably passed through a filter that it may be returned to the tank for reuse. U.S. Pat. No. 4,806,237 shows a filter particularly useful for this purpose. However, even when this is done, each tank still requires its own source of water.
An object of this invention is to provide a fish farm in which two or more types an/or sizes of fish may be raised, but which requires no more water than would be required to raise a single type and/or size in a conventional tank or raceway, and, more particularly, to provide such a farm in which the fish may be grown separately in each of two or more tanks or raceways which are so constructed and arranged that the same source of water is circulated from one to the other without the need for pumps or other expensive and accident prone equipment.